276 research outputs found
A semi-numerical method for periodic orbits in a bisymmetrical potential
We use a semi-numerical method to find the position and period of periodic
orbits in a bisymmetrical potential, made up of a two dimensional harmonic
oscillator, with an additional term of a Plummer potential, in a number of
resonant cases. The results are compared with the outcomes obtained by the
numerical integration of the equations of motion and the agreement is good.
This indicates that the semi-numerical method gives general and reliable
results. Comparison with other methods of locating periodic orbits is also
made.Comment: Published in Mechanics Research Communication journal, 6 pages, 5
figures and 6 table
Revealing the influence of dark matter on the nature of motion and the families of orbits in axisymmetric galaxy models
An axially symmetric galactic gravitational model composed of a dense,
massive and spherical nucleus with an additional dark matter halo component was
used, to distinguish between the regular and chaotic character of orbits of
stars that move in the meridional plane (R,z). We investigated two different
cases: (i) a flat-disk galaxy (ii) an elliptical galaxy. It is of particular
interest to reveal how the portion of the dark matter inside the main body of
the galaxy influences the ordered or chaotic nature of motion. Varying the
ratio of dark matter to stellar mass, we monitored the evolution not only of
the percentage of chaotic orbits, but also of the percentages of orbits that
compose the main regular resonant families, by classifying regular orbits into
different families. Moreover we tried, to reveal how the starting position of
the parent periodic orbits of each regular family changes with respect to the
fractional portion of dark matter. We compared our results with previous
similar work.Comment: Published in Astronomy & Astrophysics (A&A) journal. arXiv admin
note: previous paper with related context: arXiv:1309.560
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